Phenotypic and Genotypic screening of fifty-two rice (Oryza sativa L.) genotypes for desirable cultivars against blast disease

Magnaporthe oryzae, the rice blast fungus, is one of the most dangerous rice pathogens, causing considerable crop losses around the world. In order to explore the rice blast-resistant sources, initially performed a large-scale screening of 277 rice accessions. In parallel with field evaluations, fifty-two rice accessions were genotyped for 25 major blast resistance genes utilizing functional/gene-based markers based on their reactivity against rice blast disease. According to the phenotypic examination, 29 (58%) and 22 (42%) entries were found to be highly resistant, 18 (36%) and 29 (57%) showed moderate resistance, and 05 (6%) and 01 (1%), respectively, were highly susceptible to leaf and neck blast. The genetic frequency of 25 major blast resistance genes ranged from 32 to 60%, with two genotypes having a maximum of 16 R-genes each. The 52 rice accessions were divided into two groups based on cluster and population structure analysis. The highly resistant and moderately resistant accessions are divided into different groups using the principal coordinate analysis. According to the analysis of molecular variance, the maximum diversity was found within the population, while the minimum diversity was found between the populations. Two markers (RM5647 and K39512), which correspond to the blast-resistant genes Pi36 and Pik, respectively, showed a significant association to the neck blast disease, whereas three markers (Pi2-i, Pita3, and k2167), which correspond to the blast-resistant genes Pi2, Pita/Pita2, and Pikm, respectively, showed a significant association to the leaf blast disease. The associated R-genes might be utilized in rice breeding programmes through marker-assisted breeding, and the identified resistant rice accessions could be used as prospective donors for the production of new resistant varieties in India and around the world.


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• If neither of these applies but you are able to provide details of access elsewhere, with or without limitations, please do so. For example: Data cannot be shared publicly because of [XXX]. Data  prevailing pathogen races to use the most successful ones in the rice breeding programme to combat 100 blast disease. The present study was carried out to explore the genetic association of 25 mapped re-101 sistance genes in 52 rice accessions, including released varieties, advanced breeding materials, and tra-102 ditional rice varieties using linked/functional markers. The main goal of this study was to find an asso-103 ciation between the leaf and neck blast R genes, which impart blast resistance to these lines, and novel 104 blast resistance donor sources (R genes/alleles).  Similarly, the other set was also tested for neck blast disease, but Bala was used as a susceptible 1X Taq buffer, 1U Taq DNA polymerase, and nuclease-free water were used in the PCR amplification.

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The PCR conditions were set as follows: initial denaturation at 94 °C for 5 minutes was followed by 35  for the PCR analysis as presence (1) or absence (0).

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Allele scoring and genetic diversity analysis 156 The presence or absence of an allele was indicated as 1 and 0, respectively, in the amplified PCR 157 products of 25 markers, which were scored as a binary matrix. Using a binary data matrix of 25 markers, 158 the genetic distance and similarity coefficients for 52 rice accessions were calculated. Using the Cervus   Of 52 rice genotypes, 29 (58%) and 22 (42%) rice genotypes were found to be highly resistant, 18 (36%) and 29 (57%) were moderately resistant, while 05 (6%) and 01 (1%) were highly susceptible to leaf and neck blast, respectively. Incidentally, sixteen genotypes showed high resistance to both leaf and neck blasts (Fig 1). The present study used a set of twenty-five markers (functional/linked markers) that corresponded 203 to the twenty-five R genes (Table 3). The gene frequency of the twenty-five blast R genes ranged from chromosome 9 was detected using the gene-specific marker CRG4-2, which was found in 23 genotypes.

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Using the linked marker RM5647, the blast resistance genes Pi36 (chromosome 8) were discovered in 12 genotypes. The Pi49 gene, which is located on chromosome 11, was found in 12 genotypes after 182 219 bp were seen with the RM6094 marker. Using the RM5364 primer, the Pi48 gene was discovered in 220 five genotypes.

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The R genes, Piz, and Piz-t on chromosome 6 were amplified using SNP markers Z56592 and    (Table 5). For leaf blast, the associated markers showed a phenotypic variance of 7.2% to  estimation for leaf and neck blast disease based on 25 markers. The Adhoc Measure K peak plateau was discovered to be K = 2 (Fig 2), indicating that the complete 52 rice genotypes were divided into two subgroups (SG1 and SG2).
All populations were divided into two major subgroups with eight admixture levels based on an ancestry threshold of >60 % (Table 6). SG1 was made up of the most genotypes identified to be highly resistant to neck blast. The majority of genotypes identified to be highly resistant to leaf blast, on the other hand, were concentrated in SG2. Genotypes with moderate resistance to both leaf and neck blast were clustered together in SG2, while genotypes with high susceptibility to both leaf and neck blast were grouped together in SG1.  PCoA analysis has been carried out to establish the genetic relationship among the rice genotypes.

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PCoA analysis revealed that the first two axes explained 17.18 % and 12.29 % of the total variance 294 (Table 7 and Table 7 Percentage of variation explained by the first 3 axes using blast resistance gene in PCoA.  tional genes or alleles that will help to overcome the disease and ensure future rice harvests [12,37].

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The present experiment investigated the genetic diversity of released varieties, advanced breeding ma-321 terials, and traditional rice varieties for blast resistance genes using 25 molecular markers.

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In this study, we used functional/gene-based molecular markers to genotype fifty-two rice hill The leaf and neck blast-resistant genotypes are found in the first and second quadrants of the PCoA 385383 analysis, whereas moderately resistant genotypes were found in the first, third, and fourth quadrants.
386384 Previous research has also divided resistant and susceptible germplasm into distinct categories [40,47]. 387385 A statistical approach for estimating molecular variance in a single species is the analysis of molecular Formatted: Space Before: 6.3 pt